We take this to be the name of the sender of a letter. a Flauio Ceriali is impossible and there is at least one letter after ceriali. As this letter is compatible with s, we suggest that we have an analogous text to 301, i.e. a letter written by a slave of Cerialis; the name of the slave is irrecoverable.
Below are traces of a further line, which is illegible but can hardly be anything other than part of praefecti, perhaps abbreviated. The other side is blank.